As known well, boilers have been used for heating rooms and supplying hot water at home or in public buildings. Generally, an instantaneous boiler is used for the supply of heating water and hot water. The instantaneous boiler is recognized to mainly supply heating water and additionally to supply hot water. However, with the improvement of adiabatic performance in houses, there is a tendency that the capacity of the boiler necessary for heating rooms is reduced, but the requirement for hot water supply increases.
Generally, the instantaneous boilers use a double pipe heat exchanger or a single pipe heat exchanger. The double pipe heat exchanger refers to one in which a hot water heat exchanging pipe is inserted into a heating water heat exchanger. The single pipe heat exchanger refers to one in which a hot water heat exchanger and a heating water heat exchanger are separately installed.
Since the double pipe heat exchanger has a compact size in comparison with the single pipe heat exchanger, it is possible to manufacture a boiler with a compact size and high heat efficiency, thereby reducing a manufacturing cost.
FIG. 1 is a view showing a configuration of a conventional boiler with a double pipe heat exchanger, and FIG. 2 is a view showing a configuration of a conventional boiler with a single pipe heat exchanger.
In the conventional boiler, a burner 20 is disposed at a lower portion of a combustion chamber 10. A heat exchanger 30 is installed at an upper portion of the burner 20. Therefore, heat energy generated from the burner 20 is transferred to the heat exchanger 30 including pipes through which water generally flows.
As shown in FIG. 1 attached hereto, the conventional double pipe heat exchanger includes an outer pipe 31 used for heating water pathway and an inner pipe 32 used for hot water pathway. In the conventional double pipe heat exchanger, combustion heat is firstly transferred from the burner 20 to the outer pipe 31 and then is secondly transferred to the inner pipe 32.
The conventional boiler with the double pipe heat exchanger has been designed in which a heating water line 50 is interrupted by means of a three-way valve 40 in order to rapidly supply hot water when a user uses the hot water so that combustion heat of the burner 20 is transferred to the inner pipe 32 through the outer pipe 31.
As shown in FIG. 2 attached hereto, the conventional boiler with the single pipe heat exchanger has a structure in that combustion heat of a burner 20 is transferred to a single pipe. In the conventional boiler, water of the single pipe is heated by means of the burner 20 and the flow of the water to a heating water line 50 is interrupted by a three-way valve 40 when a user uses hot water. At this time, an indirect heat exchanging line 70 is open so that the heated water flows to an indirect hot water heat exchanger 60.
Since the two conventional boilers have a structure in that a heating water pathway firstly absorbs the combustion heat of the burner 20, output of hot water is always lower than that of heating water. Further, if only hot water is used, a circulation pump 80 operates unnecessarily, thereby increasing consumption of electricity.
In addition, there is a problem in that an operation of heating rooms can be stopped during use of hot water. Further, since the three-way valve 40 is used for increasing the supply efficiency of the hot water, there is a problem in that the pipe arrangement is complicated, thereby increasing a manufacturing cost of the boiler.